Trim the ends off of the brussels sprouts and discard. Cut them in half.
Place the halved sprouts in a bowl and toss with olive oil, kosher salt and garlic powder until coated.
Add grated cheese to a sheet pan (no parchment paper is needed if it's a newer nonstick sheet pan) in a thick even layer.
Place the brussels sprouts cut side down and press into the cheese.
Bake for 30 minutes, turning the sheet pan (not the sprouts!) half way through, until the cheese is crispy and golden brown and the brussels sprouts are tender.
Remove from heat and let rest for 5-10 minutes for the cheese to firm up. Then tear the crispy parmesan crusted brussels sprouts into bite sized pieces and serve.